You can achieve a quite good performance with showing a simple gif in your layout. Just create a gif out of the images you have (use some gif maker for that - there are a ton of other options, just search for it). For showing the gif in your application you can use a custom library, like android-gif-drawable. Implementation is similar to an ImageView:
<pl.droidsonroids.gif.GifImageView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:src="@drawable/your_butterfly_anim"
/>
It's a possibility for simple animations.
Edit:
int distance = 100; //the distance to move in pixels
int duration = 500; //the duration of the animation in ms
double direction = Math.random() * 2 * Math.PI;
int translationX = Math.cos(direction) * distance;
int translationY = Math.sin(direction) * distance;
yourImageView.animate().translationX(translationX).translationY(translationY).setDuration(duration).start();
This should give you some first ideas of how you can get it flying randomly.